Web decurling apparatus



May 25, 1965 P. ZERNOV ETAL WEB DECURLING APPARATUS 2 Sheets-Sheet 1 Filed Feb. 4, 1963 INVENTORS. PETER ZERNOV BY GILBERT 8. WOYTHAL z Z l z AfroRA/EYs M y 1955 P. ZERNOV ETAL I WEB DECURLING APPQRATUS Filed Feb. 4, 1965 2 Sheets-Sheet 2 T/rl l INVENTORS- PETER ZERNOV BY G/LBERTS. WOYTHAL AffoRnEYS United States Patent 3,185,616 WEB DECURLING APPARATUS Peter Zernov and Gilbert S. Woythal, Milwaukee, Wis,

The present invention relates generally to paper converting equipment, and more particularly to a decurl apparatus for a web of paper or board which conditions the web before it is led to other apparatus such as a carton forming press, a printing press, or a hot melt applicator, or the like.

Webs of paper are furnished on a supply roll from which it is unwound as needed. The curl in such a web should be removed before the web is subjected to subsequent operations such as die cutting or printing. It is conventional to remove this curl by passing the web between two pairs of feed rolls and over a decurl bar located between such pairs of rolls.

Decurl units of this general character have heretofore been used with success, but they have certain shortcomings. For example, some of them vary the nipping pressure of one set of feed rolls in respect to the other to thereby intentionally provide slip at the nip to vary the effective tension in the Web as it passes over the decurl bar. When depending on a certain fricional coefiicient in the nips, excessive tension in the web is developed due to different web materials having different coeflicients of friction. In other words, the friction coefiicient of the nips changes depending on the web material passing therethrough. This excessive friction overpowers the drive and overloads the gears and hearings to a point where failure of these parts occur-s.

According to the present invention, a decurl unit having two pairs of feed rolls is provided in which the nip pressure of the rolls is always positive, constant, and equal between the pairs of rolls to thereby eliminate any slip between the nips of the rolls; a slip clutch is provided between the rolls of one pair, and the amount of slip permitted by this clutch is controlled. As a result, the web tension is always proportional to the setting of the clutch, and it is unnecessary to rely on the coeflicient of friction of the web material in regarded to the nip because no reliance is placed on slipping of the nips.

A more specific aspect of the invention relates to a decurl unit of the above-mentioned type which uses a slip clutch on one of the rolls, which clutch has an airloaded brake band, the pressure of which can be manually set in proportion to the tension desired in the web.

By thus providing a definite and predetermined slip point in the feed rolls, tearing of the webs, even though of widely different composition, weight, and coefficients of friction, ha been eliminated.

These and other objects and advantages of the present invention will appear later as this disclosure progresses, reference being had to the accompanying drawings, in which:

FIGURE 1 is a side elevational view of a decurl unit made in accordance'with the present invention;

FIGURE 2 is an enlarged view of the decurl unit shown in FIGURE 1, certain-parts being shown as broken away, removed, or in section for clarity in the drawings;

FIGURE 3 is an enlarged cross-sectional view taken generally along line 3-3 in FIGURE 2.

Referring to FIGURE 1, the Web W is pulled from a stock supply roll S, over ,idler rolls I and 12, by the decurl unit D. As the web leaves unit D, it passes under a swingable speed control roll SC and then to a machine M for subsequent operation on the Web.

The decurl unit includes two vertical, spaced apart 3,185,616 Patented May 25, 1965 sides 10 and 11 between and in which are journalled a first pair of feed rolls 15 and 16, and a second pair of feed rolls 17 and 18.

One roll of each pair of rolls, namely, rolls 16 and 17, are rubber-covered and are mounted on their respective pairs of arms 20 and 21 for slight swinging movement in respect to their respective rolls 15 and 18. Rolls 16 and 17 are idler rolls and are driven only by the web.

Means are provided for continuously causing the feed rolls to exert a positive and equal nipping pressure on the web between the rolls of each pair of rolls so as to prevent any slipping of the web therebetween. This means takes the form of air cylinders for urging the rubber rolls into nipping engagement with their mating rolls 15 and 18 as follows. A pair of air cylinders 22 and 23, one at each end of the roll, act through their respective push rods 24, 25 against the arms 20. Similarly, a pair of air cylinders 26 and 27 act on the arms 21.

All four cylinders are connected together by conduit means 30 which are connected to the common valve 31. Valve 31 and consequently the air cylinders are manually regulated by a regulator 32. Thus the nipping pressure of the pairs of rolls is equal and constant.

The driven rolls 15 and 18 are smooth steel rolls, roll 18 being oversize in respect-to roll 15, by about onesixteenth of an inch on its diameter, and thus means are provided for tensioning the web between the pairs of rolls and as it passes over a decurl bar B now to be described.

The decurl bar B lays against its series of backup rollers 40 (FIG. 1) which are axially spaced along its length and absorb the thrust imposed on the bar by the web which passes thereover. The bar and its rollers are vertically adjustable in the sides 10 and 11 by the motor 41, at one side of the unit, and their pinions 42 which drive the racks 43 of the roller support frame 44. The bar B is unsupported at its ends and instead simply rests freely on its back-up rollers and is held thereagainst by the web. It has been found unnecessary to otherwise support the bar, and end bearings have been eliminated with a corresponding reduction in cost, maintenance, and friction losses.

The drive for the steel rolls 15 and 18 is as follows. A

large gear 50 is fixed to the shaft of roll 18 at the drive side of the machine, that is, the side opposite to the near side in FIGURE 1. This gear is driven from the gear 51 of a hydraulic motor M which in turn is driven by a pressure compensating pump P of the type which pumps an amount of fluid necessary to maintain a given pressure. The hydraulic pump P funishes pressure fluid via conduit 51a to this motor in an amount determined by a flow control valve 53. Valve 53 in turn is actuated by the swinging action of the speed control roll SC. More particularly, roll SC is mounted on a pair of arms 55 on a shaft 56. A counterweight CW is also fixed to shaft 56 to counterbalance the weight of roll SC. The amount and direction of rotation of shaft 56 regulates the flow control valve. In other words, when the roll SC is down,

then the valve 53 is off. As the roll SC moves upwardly in response to demand for the web as determined by the machine (not shown) to which the web is being fed, the valve 53 is opened accordingly which permits fluid to go to the motor. More specifically, as the valve is opened or closed, the amount of fluid delivered by the pressure compensating pump P to the motor varies accordingly. Thus, no by-pass of fluid is necessary with the present arrangement and the loop of the web or the roll SC is not used for that purpose, to thereby slow down the two sets of feed rolls. Instead, rotation of shaft 56 controls the full volume of fluid of the pump P which drives the motor M, that is, flow control valve 53 determines the amount of fluid delivered by the pump and which flows via conduit 53a to the valve 53 and then via conduit 53b to the pump reservoir.

In the above manner, driving power is furnished to feed roll 18. This power is transmitted from gear 5% of roll 18 to a gear '60 that is fixed to the outer member'or drum 61 of a slip clutch C which in turn is mounted on shaft 63 of roller 15, for driving the latter as follows.

The clutch C is mounted by its hub 64 and antifriction ball bearing assemblies 65 and 66 on the shaft 63. Gear 64 and drum 61 are rigidly secured to this hub by their respective cap bolts 67 and 68.

The vented drum 61 constitutes the outer member of the clutch and has an internal, cylindrical surface 69.

Mounted within the drum is an inner member of the clutch in the form of a cylindrical element 70 which is fixed by key 71 to the shaft 63 for rotation therewith. An expandable and pressurizable chamber member 72 is fixed around the periphery of element 70, and a friction band 73 surrounds this chamber member and is urge thereby into engaging contact with the inner surface of the outer clutch element.

Air pressure is introduced into chamber member 72 via the conduit 74 which is in communication, via the drilled passages 75 and 76 in the end of shaft 63 and rotary seal unit 77 with a conduit 78 that leads to a valve 79 which in turn is regulated by the manually adjustable regulator 89. Regulator 80 receives air pressure through conduit 81 from a source (not shown).

The air-loaded brake band 73 can thus be permitted to slip in its drum in any desired amount.

The amount of web tension required in order to slip the clutch elements is determined by the air pressure which in turn is manually adjusted depending on the maximum tension permitted in the web.

It will be recalled that the nipping pressure between the feed rolls is constant, and it should be noted that the only slipping that occurs is in the slip clutch. It is not necessary to depend on friction in the hips, which changes with the friction coefficient of the material of the web being treated, in order to control maximum web tension. Instead, the tension setting in the web is always propor tional to the air pressure setting on the slip clutch.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

We claim:

1. Web decurling apparatus comprising, two spaced pairs of feed rolls in nip forming relationship with said web, a decurling member disposed between said pairs of rolls against which the web is fed as it passes from one pair of rolls to the other, drive means for driving said pairs of feed rolls, the pair of feed rolls at the output side of said decurling member feeding the web at a higher speed than that of the other pair of produce a tension in the web as it passes over said decurling'member, and

common control means for continuously causing said rolls to exert a positive and equal nipping pressure on the web between the rolls of each pair of rolls so as to prevent any slipping of the web therebetween, said drive means including a slip clutch between said pairs of feed rolls.

2. Web decurling apparatus comprising, two spaced pairs of feed rolls in nip forming relationship with said web, a decurling member disposed between said pairs of rolls against which the web is fed as it passes from one pair of rolls to the other, the pair of feed rolls at the output side of said decurling member feeding the web at a higher speed than that of the other pair to produce a tension in the web as it passes over said decurling member, common control means'for continuously causing said rolls to exert a positive and equal nipping pressure on the vent any slipping of the web therebetween, mean for driving one roll of one pair of feed rolls, and drive means including a slip clutch between said one roll and one of the rolls of the other pair of feed rolls.

3. Web decurling apparatus comprising, two spaced pairs of feed rolls in nip forming relationship with said web, a decurling member disposed between said pairs of rolls against which the web is fed as it passes from one pair of rolls to the other, drive means for driving said pairs of feed rolls and including a slip clutch between said pairs, the pair of feed rolls at the output side of said decurling member feeding the web at a higher speed than that of the other pair to produce a tension in the web as it passes over said decurling member, one roll of each pair of rolls being swingably mounted in respect to its mating roll, air cylinders for swinging said one rolls for continuously causing said pairs of rolls to exert a positive and equal nipping pressure on the web between the rolls of each pair of rolls so as to prevent any slipping of the web therebetween, and common regulating means for said air cylinders.

4. Web decurling apparatus, two spaced pairs of feed rolls in nip forming relationship with said web, a decurling member disposed between said pairs of rolls against which the web is fed as it passes from one pair of rolls to the other, means including said feed rolls for tensioning the web as it passes over said decurling member, common control means for continuously causing said rolls to exert a positiveand equal nipping pressure on the web between the rolls of each pair of rolls so as to prevent any slipping of the web therebetween, a hydraulic motor for driving one roll of one of said pairs of rolls, a pressure compensating hydraulic pump for driving said motor, a flow control 'valve for regulating the output of said pump, actuating means for said valve and responsive to the demand for the web at the output side of said apparatus, and drive means including a slip clutch between said one roll and a roll of the other of said pair of feed rolls.

5. Web decurling apparatus, two spaced pairs of feed rolls in nip forming relationship with said web, a decurling member disposed between said pairs of rolls against which the web is fed as it passes from one pair of rolls to the other, 'drive means for driving said pairs of feed rolls and including a slip clutch between said pairs of rolls, means including said feed rolls for producing a tension in the web as it passes over said decurling member, one roll of each pair of rolls being swingably mounted in respect to its mating roll, air cylinders for swinging said one roll of each pair of rolls for continuously causing said pairs of rolls to exert a positive and equal nipping pressure on the web between the rolls of each pair of rolls so as to prevent any slipping of the web therebetween, common regulating means for said air cylinders, a hydraulic motor for driving one roll of one of said pairs of rolls, a pressure compensating hydraulic pump for driving said motor, a flow control valve for regulating the output of said pump, and actuating means for said valve and responsive to the demand for the web at the output side of said apparatus.

References Cited by the Examiner UNITED STATES PATENTS r 1,729,272 9/29 King 117-7 2,658,432 11/53 Baumgartner 162-271 2,737,089 3/56 Baumgartner l62--27l 2,918,897 12/59 Zernov 16227l DONALL H. SYLVESTER, Primary Examiner,

MORRIS O. WOLK, Examiner. 

1. WEB DECURLING APPARATUS COMPRISING, TWO SPACED PAIRS OF FEED ROLLS IN NIP FORMING RELATIONSHIP WITH SAID WEB, A DECURLING MEMBER DISPOSED BETWEEN SAID PAIRS OF ROLLS AGAINST WHICH THE WEB IS FED AS IT PASSES FROM ONE PAIR OF ROLLS TO THE OTHER, DRIVE MEANS FOR DRIVING SAID PAIRS OF FEED ROLLS, THE PAIR OF FEED ROLLS AT THE OUTPUT SIDE OF SAID DECURLING MEMBER FEEDING THE WEB AT A HIGHER SPEED THAN THAT OF THE OTHER PAIR OF PRODUCE A TENSION IN THE WEB AS IT PASSES OVER SAID DECURLING MEMBER, AND COMMON CONTROL MEANS FOR CONTINUOUSLY CAUSING SAID ROLLS TO EXERT A POSITIVE AND EQUAL NIPPING PRESSURE ON THE WEB BETWEEN THE ROLLS OF EACH PAIR OF ROLLS SO AS TO PREVENT 